Implemented PocketPC menubar/toolbar as wxToolMenuBar derived
from wxToolBar, solving the problem of how normal toolbars
can co-exist with combined ones. Tidied up WinCE toolbar code.
Implemented wxToolBar as 'dummy' toolbar under Smartphone.
Dialogs now show an empty menubar to hide inactive one
underneath.

Unlike the preferences item which should only be enabled if it exists and is enabled, the quit item should be enabled unless it both exists and is disabled, otherwise Quit will not be enabled unless the application specifically adds wxID_EXIT. This should fix David's bug but still retain the old functionality. [ modified previously committed patch 1160343 ]

Frames have Ctrl+Q accelerator set automatically, as per the
PocketPC guidelines
Documented issues in manual under wxWinCE topic.
wxDEFAULT_DIALOG_STYLES rationalised so we can make use of
styles such as wxCLOSE_BOX in future (OK button on titlebar)
Added Set/GetAffirmativeId and DoOK so that titlebar OK button
can be customised